Technical Field
The present disclosure relates to methods of transferring a graphene sheet comprising one or more layers of graphene. More specifically, the present disclosure relates to methods of transferring a graphene sheet comprising one or more layers of graphene formed on a metal film, such as a copper film, coating a surface of a metal or alloy substrate onto a target substrate.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, is neither expressly nor impliedly admitted as prior art against the present invention.
Conventional transparent conducting electrodes commonly used in solar cells, touch sensors and flat panel displays make use of indium tin oxide (ITO). ITO is an essential element in virtually all flat-panel displays, including touch screens on smart phones and iPads, and is an element of organic light-emitting diodes (OLEDs) and solar cells. The element indium is becoming increasingly rare and expensive. ITO is also brittle, which heightens the risk of a screen cracking when a smart phone is dropped, further ruling ITO out as the basis for flexible displays.
Graphene is an allotrope of carbon in the form of a two-dimensional, atomic-scale, hexagonal lattice in which one atom forms each vertex. Graphene sheets comprising one or more layers of graphene are flexible, about 207 times stronger than steel by weigh, and nearly transparent, and conduct heat and electricity efficiently. The capability of producing high-quality graphene sheets on a large scale has become a key factor in commercializing graphene-based technologies. The stable and excellent mechanical, electrical, and chemical characteristics potentially make graphene sheets with one or a few layers of graphene a cost-effective replacement for ITO as highly conductive, transparent, and flexible electrodes in electronic devices, such as displays and photovoltaic cells. In particular, a highly conductive, transparent, and flexible electrode made from a continuous monolayered graphene thin film can be of high value in electronic devices.
Current techniques for producing graphene devices involve the use of photolithography or e-beam lithography to produce graphene devices having the necessary structures. Some of the disadvantages of these processes include high processing cost, long processing time, low yield, and unwanted doping of graphene. In addition, these processes are not compatible with flexible polymer substrates widely used for touch screens, electronic paper and displays, photovoltaics, lighting, and sensor tags.
It is an object of this disclosure to provide methods of transferring a graphene sheet comprising one or more layers of graphene formed on a metal film, such as a copper film, coating a surface of a metal or alloy substrate onto a target substrate, particularly a flexible target substrate, at the scale and quality required for applications in high performance nanoelectronics and optoelectronics.